Abstract

The prediction of emerging infectious diseases (EIDs) and the avoidance of their tremendous social and economic costs is contingent on the identification of their most likely drivers. It is argued that the drivers of global environmental change (and climate change as both a driver and an impact) are often the drivers of EIDs; and that the two overlap to such a strong degree that targeting these drivers is sound epidemiological policy. Several drivers overlap with the leading causes of biodiversity loss, providing opportunities for health and biodiversity sectors to generate synergies at local and global levels. This chapter provides a primer on EID ecology, reviews underlying drivers and mechanisms that facilitate pathogen spillover and spread, provides suggested policy and practice-based actions toward the prevention of EIDs in the context of environmental change, and identifies knowledge gaps for the purpose of further research.

Background: A Primer On Pathogens

We can examine infectious disease emergence on both micro- and macro-levels. On a microscopic (or single pathogen) level, emergence events may have complex mechanisms, prompting various theories about different factors that may lead to disease emergence and spread and their relation to changes in biodiversity or species composition in an ecosystem (Keesing, Holt, & Ostfeld, 2006; Randolph & Dobson, 2012). While microlevel analyses and their interactions with macrolevel processes are useful, the thematic focus of this chapter is on the macrolevel, where emergence is driven by the many anthropogenic impacts that are altering ecological dynamics on a large scale, leading to global environmental change. For example, land conversion for agricultural uses and livestock production and other anthropogenic activities have increased or led to new types of human or domestic animal contact with wildlife, thereby facilitating pathogen “spillover” to humans (Jones et al., 2008; Karesh et al., 2012). At the same time, the rapid expansion in trade and travel in recent decades also establishes new pathways for the spread of dangerous pathogens, including through the introduction of invasive species and the climatic and other habitat conditions that allow them to persist (Mazza, Tricarico, Genovesi, & Gherardi, 2014). To examine the broad drivers leading to disease emergence, a basic comprehension of infectious disease dynamics is needed.